Nalini Nadkarni didn’t play with Barbies as a girl. She was too busy climbing the maple trees in her front yard in Bethesda, Md.

The forest ecologist might seem an unlikely person to help design and promote Barbie dolls. But over the past six months, she has been inspiring girls worldwide to play with dolls that sport a magnifying glass and all-terrain boots instead of tiaras and high heels. The new explorer Barbie dolls were designed with her input by Mattel and National Geographic.

The dolls, which include an astrophysicist, a conservationist, an entomologist, a marine biologist and a nature photojournalist, are long overdue, said Nadkarni, 65. Nadkarni is a University of Utah biology professor who studies rainforest canopies and how plants get their nutrients.

“When I was growing up in Bethesda, we tried to live simply, following Gandhi’s principles,” she said. “My dad was from India, and a Barbie didn’t quite fit in with living a simple life.”

Instead, she and her four siblings were encouraged by their mother, who was a stay-at-home mom, and their father, a pharmacologist, to create their own fun.

For Nadkarni, that meant tree climbing.

“As a child, I had a vivid imagination and could picture the treetop as a place of rescue if the neighborhood flooded, or as a hospital for wounded birds,” she said. “Because no one else I knew climbed trees. It was my own world, and I could be anything in it.”

Nadkarni is doing research in Costa Rica on trees that are still standing after farmers cut down the majority of the forest on their land.

It has never been more important, Nadkarni said, to share what she has learned with a new generation.

“These explorer Barbies are a big step forward,” she said. “It’s not perfect — Barbie still has that impossible body shape and is made of plastic — but it’s a good start.”

Nadkarni said she had spent years trying to persuade the toy company to develop a “treetop Barbie,” with no luck.

“In 2003, I’d been thinking of ways to help get girls more interested in science, and I asked myself, ‘What do girls care about when they’re little?’ ” she recalled.

She looked to her young daughter.

“I knew that girls wanted to play with Barbies and look like Barbies,” Nadkarni said. “But what if Barbie had field clothes on and came with a little booklet about canopy plants?”

Mattel wasn’t interested in her idea. Nadkarni said she was told that a “treetop Barbie” wouldn’t sell, but she persisted.

Since sales of the explorer Barbies began in the summer at the National Geographic website and at retailers such as Target and Walmart, Nadkarni has heard from girls coast to coast, thanking her for her work in tropical rainforests and asking questions about how they can make a difference to help trees in their own communities.

Nadkarni has since held ecology discussions with about a dozen elementary school classrooms across the country, hoping to pass along her passion for caring for the environment and the world’s endangered forest canopies.

“When I started hearing from these young kids, I realized they had a true sense of the dire straits of our forests,” she said. “They really care, and they want us grown-ups to do something to save our environment. It gives me hope for the future that girls — and boys — as young as 7 and 8 want to do what they can to help.”